'Doomsday Glacier' vulnerability seen in new maps

Doomsday my foot.  As the map shows, the glacier is in the middle of volcanic hotspots.  So it does show some melting from that cause. But it has had volcanoes under it for a long time.

And volcanoes wax and wane.  The volcanic activity will drop off at some stage and the glacier will expand again

Scientists may just have identified Thwaites Glacier's Achilles heel.

This Antarctic colossus is melting at a rapid rate, dumping billions of tonnes of ice in the ocean every year and pushing up global sea-levels.

Now, a UK-US team has surveyed the deep seafloor channels in front of the glacier that almost certainly provide the access for warm water to infiltrate and attack Thwaites' underside.

It's information that will be used to try to predict the ice stream's future.

"These channels had not been mapped before in this kind of detail, and what we've discovered is that they're actually much bigger than anyone thought - up to 600m deep. Think of six football pitches back to back," said Dr Kelly Hogan from the British Antarctic Survey (BAS).

"And because they are so deep, and so wide - this allows a lot more water to get at, and melt, Thwaites' floating front as well as its ice that rests on the seabed," she told BBC News.

Why is Thwaites Glacier so important?

Flowing off the west of the Antarctic continent, Thwaites is almost as big as Great Britain.

It's a majestic sight, with its buoyant front, or "ice shelf", pushing far out to sea and kicking off huge icebergs. But satellite monitoring indicates this glacier is melting at an accelerating rate.

In the 1990s it was losing just over 10 billion tonnes of ice a year. Today, it's more like 80 billion tonnes. The cause of the melting is thought to be the influx of relatively warm bottom-water drawn in from the wider ocean.

Currently, Thwaites' ice loss contributes approximately 4% to the annual rise in global sea-levels, with the potential to add 65cm in total should the whole glacier collapse.

No-one thinks this will happen in the short-to-medium term, but Thwaites is considered particularly vulnerable in a warming world, and scientists would like to know precisely how fast any changes might occur.

What does the latest research show?
The UK and the US joined forces in 2019 to investigate Thwaites.

Their scientists sailed a ship equipped with an echo-sounder right up to shelf's ice cliffs, to trace the shape of the seabed below.

A plane was also flown back and forth across the shelf to measure small variations in the pull of gravity. These deviations reflected the seafloor's undulations under the shelf.

The two datasets taken together now provide the best view yet of Thwaites' underlying topography.

"The connected channels that we've mapped in detail for the first time are the potential pathways for deep-ocean warm water to get in and do damage at that point where the glacier is still grounded on the seabed, where it begins to lift up and float," explained BAS colleague Dr Tom Jordan, "but also to melt the base of the ice shelf, which if you weaken will make the ice further upstream in the glacier flow faster."


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